Origin

We have had sheep in the language since Anglo-Saxon times, but perhaps surprisingly people did not start using the word to mean ‘someone too easily influenced or led’ until the 16th century. The expression to separate the sheep from the goats, ‘to divide people or things into superior and inferior groups’, is a biblical reference to the account of the Last Judgement in the Gospel of Matthew. There the apostle describes how all the nations of the world will be gathered before God and how ‘He shall separate them one from another, as a shepherd divideth his sheep from the goats: And he shall set the sheep on his right hand, but the goats on his left.’